This invention is concerned with the production of high purity radioiodine for thyroid measurements and as a general radionuclide. The invention is particularly directed to the utilization of a heat pipe in the production of radioisotopes using very intense particle accelerators.
Radioactive iodine is used for medical diagnostic studies. The isotope .sup.131 I has been used for this purpose because of its availability. The radioisotope .sup.123 I is considered much superior to the .sup.131 I in studies where the amount of radiation exposure to a patient is of prime concern. Because of the shorter half-life and the decay by electron capture, the radiation exposure received by the patient from .sup.123 I is about one-fortieth that of an equal amount of .sup.131 I.
.sup.123 I is also superior to .sup.131 I because the gamma ray energy of .sup.123 I is 159 KEV compared to 364 KEV of .sup.131 I. Collimators operate more effectively with this lower energy. Also the collimators used with .sup.123 I are less bulky.
A method of .sup.123 I production is disclosed in U.S. Pat. No. 3,694,313. The method disclosed in this patent has been quite successful in terms of freedom from radioactive impurities. However, the method is not capable of handling the power densities involved in using high energy, high current machines.